Railway-traffic-controlling apparatus



1,619,221 March 1927' H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 2, 1924 2 Sheets-Sheet 1 March 1, 1927. 1,619,221

H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS FiledSep t. 2, 1924 2 Sheets-Sheet 2 Passezzyer 72 0222 INVENTOR l atented Mar. 1, i927.

pairs STATES raisin PATENT orricey HOWARD A. 'rrrorirson, or WILKINSBURG, rnNN'sYLvANra, nssreNon T rm: UNroN swi'rcir & SIGNAL ooMraNY, or SWISSVALE, PENNSYLVANIA, A conroaArroN or EENNSYLVANIA,

RAILWAY-TRAFFIG-CONTROLLING APPARATUS.

Application filed September 2, 1924. Serial No. 735,236.

My invention relates to railway traflic controlling apparatus, and particularly to apparatus of the type comprising governing mechanism on the train controlled by means located in the trackway.

Apparatus embodying my invention is in tended more specifically for stretches of railway track used having different maximums braking distances. For example, the track may be used by passengertrains having relatively short iaximum braking distances, and also by I freighttrains having relatively long maximum braking distances. In order to bring these two classes of trains from a given speed to stop at a fixed point, the brakes on the passenger train should be'applied at one distan'ce in the rear of the fixed point and the brakes onthe freight train should be applied at a greater distance in the rear of the fixed point. One feature of my invention is the provision of means for selecting the point of brake application in accordance with the 'class of the train which-is using the track.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims,

In'the accompanying drawings, Fig. lis a diagrammatic view showingone form of trackway apparatus embodying my invention. Fig. 2 is a- View showing diagram matically a passenger V view showing diagrammatically a freight train, both of which trains are adapted to use the ailway track shown in Fig. 1.

Referring first toFig. 1, the reference characters 1 and l designate the track rails of a railway along which traffic normally 1 moves in the direction-indicated by the arrow. The stretchdrawing is the stretchbetween two adjacent stations A and A and this stretch is a complete unit of a system wh ch may be formed by placing plurality of such units end to end. When this is done, the right-hand half of station A woulc become the right-hand half of station A and so on.

The stretch of track shown in the drawing is divided by insulatedrail joints into a plurality of'sections BC, C-D, DE and E-B. The section E-B, containing the station A, is here shown as being'a gauntlet track, comprising an inner pair of rails 2, and an outer pair of rails 3. The reason for by trains of different classes train, and Fig. 3-isa of track shown in the this is that the apparatus is designed for a railway on which the freight trains are'wider than the passenger trains. If only one track were provided at the stations, and if this track were far enough away from the station platforms to permit the freight trains-to pass, then the passenger trains would be too far from the platform for safety. The gauntlet tracks are accordingly so arranged that the passenger trains take the inner track rails 2, sothat their platforms are the proper distance from the station platforms, whereas the freight trains take the outer track rails 3, so that they clear the stationplatforms by a'safe margin. Located at the right-hand end of each gauntlet track is a switch N, and located at the left-hand end of each gauntlet track is a switch. h These switches are operated by suitable means, not shown in the drawing for the reason that such means forms no part ofmy present invention. It

is, of course, understood that in practice the two switches for each gauntlettrack willbe operated simultaneously. lVhen a passenger train approaches a station the two switches will be in normal positions, so that this train will take the inner track rails 2, whereas,

when a freight train approaches a station the two switches will be in reverse positions, so that 1 this train will take the .outer track rails 3.

Each track section is provided with a track circuit comprising a source of current lo cated at the .eXit end of the section and a track relay located at the entrance end of the section. As here shown, the source of track circuit current is a track transformerdesignated by the reference character G with an exponent corresponding to the location, the secondary of which transformer 1S connected directly across the track rails through a current-hm1tmg lmpedance 5. The track relay for each section is designated by the reference character H witn an exponent corresponding to the location. The two gauntlet tracks 2 and 3 at each station are connected in multiple by bonds so that a train on either track will open the track relay H 1 The primary of each track transformer G is connected with the secondary of an adjacentline transformer designated by the reference oharacterF wlth an exponent corresponding to the location, and the primary of each line transformer F connected with a transmn- Ill ,P" is closed w sion line L which is constantly supplied with alternating current hy a generator M.

Located at the point B is a signal S, which governs trallic through the stretch l:3-Cl. This signal in the form here shown is a threeposition semaphore signal arranged to indicate stop, caution and proceed. This signal is controlled by the adjacent track relay H and also by relays J and P. The control of the two latter relays, is as follows: Relay J is provided with a circuit which passes 'lrointhe secondary ol trans'torlner F, through wires 17 and 18, contact ll) of track relay H, wires 20 and 21, winding of relay (l, wire wire (3, couuuon wire 0.

- and wires 2?) and 25 to the secondary oil transformer F. It tollows that relay J is a repeater For track relay ll" and will therefore he energized at all times except when section -l is occupied.

Relay l is provided with a circuit which passes from the secondary ot transformer F, through wires 26 and 527,, front point of contact oi track relay ll, wires 2.) and 30, front point of contact 31 of track relay li wires 32 and 33, contact 3st of relay H wires 35 and 236, winding oil relay 1 wires 37 and (Lconunon wire (hand wires 35 and ell) to the secondary ot' transloriuer F. It follows that so far as thiseircuit is con cerned, relay P will he (lo-energized whenever any one ot the track relays ll, H or ll is (lo-energized, that is, whenever there is a train at any point hetween I3 and E. Belay l is provided with a stick circuit which passes from transformer F through wires 17 and 11.8, contact 11) of relay I-ll, wires .30 and 2(7), hack point oi contact (35 oi relay ill, wire (it, contact (53, wires (52 and till, winding; of relay l and wires 37, 6,0. 23 and 25 to transformer I It relay train enters section lrl--(l it will remain closed until the train leaves this section hecause o I this stick circuit. lies lay l may he made ruilliciently slow-rcleasing to bridge the. interval hetwcen. the opening of its pickupcircuit at contact ill and the closing ol its stii-lc circuit at contact 65, or the contacts oil' relay ll may he so adjusted that the hack point of coutactlll'i closes he'lore contact Ell opei Relay P is provided with other circuits which will he explained hereinajl'ter.

Signal S is iirovidea with a caution indication circuit which pas from the secondary of transformer I through wires: and T contact 8 oil? relayrl, wire 9, ciiintact of relay ll, wires ll and it the operat- 111;: mechanism of signaltl, and wire 13 to the secondary of transformer 1 This signal is also provided with :1 proceed indication circuit which passes from the secondary of transformer F wires (3 and T, contact 8 of relay J, wire 9, contact 10 of relay H, wires 11 and lhcontaet of i l; oi track relay ll;

relay P wire 16, operating mechanism of signal if), and wire 13 to secondary of transformer F". It follows that when either track section l.l-C or C-d) is occupied by a train, signal S" will indicate stop because either relay ll" or relay J will then he doenergizcd and so the caution indication circuit for signal S will he opened at either contact '10 or 8. It also follows that in so far as the circuits thus far traced for relay 1? are concerned, signal S will indicate procetal only when sections lL-C, (Pd) and l)-l l are unoccupied. That is to say, it there is a train in section [)-E but no train in the other two sections, relays H and J will he energized, so that the caution indi cation circuit for signal b" will he closed, hut relay i will he tle e1iei'grize(l so that the proceed indication circuit for this signal will he open at contact 15.

Each track section is provided with means :tor Sumplying an alternating train governing current to the two rails of the section in multiple, which current I will hereinafter term the loop current. For this purpose each section between stations is provided with a resistance U connected across the rails adjacent the entrance end of the section, a resistance V connected across the rails at an intermediate point in the section, and a resistance W connected across the ends of the rails at the exit end of the section. Section PL-ll, which section contains the station with the gauntlet track, is provided with only two oi these resistances, U and \V, located adjacent the entrance and exit ends of the section respectively. Referring particularly to section l l-(l, the loop current for this section is supplied by a transformer it. When track relay H" is energized, the loop circuit is from the secondary of trans- 't'ornier it, through wire 13. front point of contact -l- 2lol trach relay ll, wire to, rt sistance l, the track rails of section ,tl--C J11 inultiplc, resistance ii, and wire is to the secondary or transformer ii". When track relay H is tie-energized. the loop circurt is train the secondary of iranslornier ii, through wire l3, hach point of contact wire a7, resistance V, the rails o'l section ,l'l -tlin inultiple, resistance U, and wire iii to thesecondary ot transformera it". The primary of trans :t'oriner l'i is su jiplied with alternating' current from the secondary ot' traristorrner F, through 1iole-chalining contacts ill) and 5:2 on relay l. When relay P is ener iacd, the circuit is l'roiu the secondary ot transllJl'liiQi F through wire (3, contact wire 50, prii'nary oil transformer lid", wire contact 52, and wire 53 to the secondary of transformer F The current which is then supplied to the loop circuit for section l -C is o'l what I will terin normal relative polarity, that is, normal instantaneous polarlift) ity with respect to the traclccircuit current supplied to the section. WVhenrela-y P is de-energized,-the' circuit is from the secondary of transformed F through wire 6, contact 49, wire 51, primary of transformer K wires 50 and 55, contact 52, and wire 58 to the secondary of transformer F The current which is then supplied to the rails of section BC is of what I will term reverse relative polarity, that is, reverse instantaneous polarity with respect to the track circuit current supplied to the section.

The loop circuits for sections C-i)- and DE, are the same as the loop circuit for section BC, the loop current for sections C-D and D-E being furnished by trans+ formers K and K respectively. The loop current for section E.B is supplied by a transformer IF, the primary of which is controlledby relay P in the same way that the primary of transformer K is controlled by relay P The loop circuit for section E-B' is controlled only by front contact 56 of track relayI I there being no resistance V at an intermediate point in this section.

"The apparatus shown in for cooperation with train-carried apparatus, which operates in. the following manner: hen a train occupies. a portion of track which 1s supplied withloop currentof normal relative polarity and also with track circuit current. the train {may proceed at a high'speed without incurring an auto-v matic application ofthebrakes. .Vlhen the train occupies a portion of track which is suppliedwith loop current of.reverse relatix e polarity and with track circuit current, the train may proceed at an intermediate speed but if it exceeds this speed it will incur an automatic application of the-brakes.

When the train occupies, a portion of track from which the supply of loopcurrentor track circuit current has been discontinued,

the train may proceed at a low speed but if; it'exceecs this speed it will incur anautomatic application of the brakes."

I. will first consider only the stretch of track between points B and E in Fig- 1, and will assume that relay P is [provided onlywith the circuits trace-d hereiubefore. If the stretch of track between points and E is unoccupied, a train movingtoward the right will receive aproceed indication throughout section B-C, because relay P is energized and will remain energized while the train is in this section, so that loop current of normal relative polarity is supplied to the rails of this section throughout the entire section. If, however, .sec' tion DE is occupied and a following train enters section BC, such following train will at once receive aca ution indication, because relay P 'is de-energized due to the fact that track r ay H is de-ene1'gizec,and'

Fig. .1 is intended so 71 0p; c ren Qt er rsez elatire po y point B if the speed is above the low value. 7

. Reverting now to the condition wherein sect-ion DE is occupied and a following train enters sections B C, it will be remembered that such following train receives a caution indication immediately after pass- 'ing point B.- A caution indication at this point is desirable when the following train is a freight tram, because of the relativelylong braking distance of trains of this class. If

the following train is a passenger train, however, a caution indication, and, consequently, the enforcement of an intermediate speed limit at. point B is undesirable, because of the relatively short braking distance for passenger trains. It accordingly becomes de sirable to delayithe caution indication until the'train reaches point C when the train is of the passenger class. To accomplish this result 1 provide the relay P with a pick-up circuit which is controlled by a transformer R located in the trackway. This transfornr eris equipped with a primary winding 57 and a secondary winding 58. The circuit for the primary winding is'froin the secondary of transformer F through wires 17 and 18, contact 19 of track relay H wires 20 andQO, wire 60, primary winding 57, wire 6, common wire 0, and wires 23 and 25 to the secondary of transformer F It will closed provided that track relay H is energized. Transformer B is provided with a magnetic clrcuit having a largeair gap and the reluctance of thisair gap isso high that unless it IS recuced by the means hereinafter explained, the current which is supplied to the pick-up circuit for relay P by secondary winding 58 is not sufficient to energize this relay Each passenger train, however, (see Fig. 2) is provided with a member Q, of magnetizable material so disposed that as thetrain passes transformer R this member passes in close proximity to iii).

the transformer and reduces the reluctance of the magnetic circuit to such value that the current supplied to relay P by the secondary windings 58 is sullicient to energize this relay. The transformer it is so located that relay P picked up before relay H opens due to the train entering section l5-C. As a passenger train passes point 13, then, relay P will become energized, and will remain energized as, long as such train orcupies any part of section li-C because of the stick circuit hereinbefore traced. in other words, with section l )E occupied, a passenger train entering section li-(l will cause relay P to be energized, so that loop current of normal relative polarity will be supplied to the passenger train throughout section i k-U. As will appear hereinafter, it' a passenger train enters section (l -l) while section D-E is still occupied, it will be unable to cause relay l to'be energized, because the circuit :l'onprimary winding of transformer It" is opened at contact as of track relayl-l", and, consequently, the passenger train will receive a caution indication immediately upon entering section l D. It will, of course, receive a stop in dication upon passing 1' lance V in this section, because track relay H is de-energized and so loop current is not supplied to section (l-l) between resistances V and w.

in describing the structure and operation of the remaining portions of the apparatus shown in Fig. 1, 1 will lirst assume that switches l and N are both in normal posiliens, that is, that'thcse switches are set up for the pass of passenger trains along the track.

Each relay P is provided with a transformer ll similar to transformer R and the pick-up circuit for each relay P including the secondary winding .38 of the associated transformer l1 the same as the pick-up circuit for relay P At location l) I have provided an auxiliary stick relay X, which is provided with a picleup circuit including an auxiliary secondary winding on trans Former ll, this pick-up circuit not being controlled b any relay contacts.

The main circuit for relayl passes from the secondary of transformer F, through wire l3, contact (36 of track relay ll, contact ti? which is closed only when switch N" in the reverse position, wire 68, contact [i l of track relay H contact which closed only when switch N 3 is in the reverse posi-- tion, contact 71 of trackrelay H, contact 72 of track relay l l winding of relay P wire 23, common wire 0, and wire 6 to the secondary of transformer F Switches N and N being in normal positions, contacts 67 and 70 are open, so that relay P is deenergized. it follows that so far as this main circuit is concerned, a train entering section C-D would receive acaution indication regardless nan of traliic conditions ahead. The circuit for primary winding 51 of transformer R" is controlled only by front point of contact 28 of relay H, and so if section E-B or BC is occupied, and the following train is a passenger train, when such train enters section (.D it will cause relay P to become en ergized. Relay P will then remain energized as long as the train in section (l D, because of the stick circuit for relay P" including contact 74 of relay P back point of contact 31 of track relay H and front point of contact :28 of track relay H This train will, therefore, receive a proceed .ii'idication through section (1-4), and will not receive a caution indication until it reaches point D.

Referringnow tOtllG apparatus at point I), the main circuit for relay P is from the secondary of transibrnier F through contact 19 of track relay H, front point of contact 65 of track relay H, contact 78, wire '77, contact 76 of track relay H contact 88, contact of track relay H winding of relay P, and common wire 0 to the secondary of transformer F 88 are operated by switches N and N, respectively, and are closed only when these switches are in the reverse positions; it being assumed that these switches are now in normal positions, these contacts are open and so relay P" is de-encrgized It follows that a train entering section D-E will receive a caution indication at point D in so far as the main circuit for relay P is concerned. lVinding 57 of transformer R is controlled by contact 79 and by contact 80 of track relay H A passenger train entering section DE will, therefore, energize relay P if sections l)l l and E-B are both unoccupied, in which event the passenger train will receive :1 proceed indication in section D-E even if section B--(] is occupied. As such train enters section DE it will cause both relays P and X to become energized, whereupon relay X will remain energized as long as the train occupies section D-E because of the stick circuit for this relay including contact of relay X and the back point of contact 28 of relay H Relay P will also remain energized by virtue of its stick circuit, which includes contact 81 of relay PD, back contact 82 of track relay H contact of relay X, contact 79, and contact 80 of track relay H Contact 79 is closed when switch N is in the normal position.

Referring now to the apparatus at point E, the main circuit forrelay P is from the secondary of transformer F through con tact 19 of track relay H contact 65 of track relay H contact 7 8, wire 77, contact 84: of track relay H winding of relay P and common return 0 to the secondary of transformer F Contact 78 being closed only when switch N is in the reverse position,

Contacts 78 and The. stick circuit for relay J.

' by a'trainin section train will receive. a caution indication at this contact is 'now open so that relay P is de-energized, and'so far as the main circuit just tracedv for this relay is concerned, a train entering section E-B will receive a caution indication. The circuit for the primary winding 5'? of transformer is controlled by normal contact 85 on switch N wire 86, and normal contact 87 on switch N, and so a passenger train entering section Iii-13 will cause relay P to be energized. is controlled only by contact 91 of this relay and back contact 92 of track relay H and so assuming that sections E-B and BG are unoccupied, the passenger train will receive a proceed indication throughout this section E-'B even thoughsectionC-D be occupied. Of course, if sectionE-B is occupied, the passenger train entering this section will receive a stop indication, such indication in fact having been received after having passed resistance V in section DE.

I will now assume that switches N and N are reversed, thereby permitting freight trains to proceed along the track. Relay P will-now become energized, because its'inain circuit becomes closed at contacts and 67,

but this circuit will be opened by a train in section C -D, D-E, E'B or B-C, so that with a train in sectio11.E'-B or B-C, a following train entering section C-D will receive a caution indication. Themain circuit for relay P now becomes normally closed at contacts 88 and 78, but with atrain in section B() or C-D, this relay will be de-energized, so that a freight train passing point D will receive a caution indication. Relay X remains de energized when a freight train passes point D, and so the stick circuit for relay P now passes from contact 81 of relay P through back contact 82 of track :relay H reverse contact 89 on switch'N and contact of track relay H It follows that if section 13-0 is occupied, a freight train willreceive a proceed indi cation at this point and through section Relay P is now normally energized because" contact 78 in its main circuit is closed, hut this relay will be ale-energized E'-B. BC or C-D;, and so with a train in section 13-0 or C -D, a' freight train entering section E 13 will .receive a caution indication.

To sum up the operation, with-section DE occupied, a freight train will receive a caution indication at B, and a stop incie cation at V' in'section C D, whereas a passenger train will receive a'caution indication at'C and a stop indication'at ,V' in" section 04). v 1

lVith" section E 13 occupied, affreight and a stopindication at V in section-DE,

whereas a passenger and train will receive a caution indication at D and a stop indication at V in section DE.

Viith section l5'-C occupied,"v a freight train will receive a caution indication at C, stop indication at E,"wh ereas a passenger trainwill receive a stop indication i /i ch section CD occupiedga freight train will receive a caution indication at D,

and a stop indication at V in section 13 -0,

whereas .a passenger train will receive a caution indication at E anda stop indication at V in section B-C.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departingfrom the spirit and scope of my invention. I

Having thus'described my invention, what I'claim is: I m 1. Railway trafiic controlling apparatus compr sing a'stretch of track used by trains of two classes having different maXiinu'm braking distances, and" means operating under unsafetraflic conditions to give a restrictive indication on an approaching train at one point ;or at another point in said stretch according as the train is of oneclass orthe other. 1

2. Railway traffic controlling apparatus comprising a stretch of rack divided into sections and used by trains of two different classes having different inaXiinum braking.

distances, and means operating when "a section is occupiedto give a restrictive indication on a-n approaching"train at one distance or another in the rearof the occupied section according asjthe trainis of one class orthe other.

3. Railwayfl'traiiic controlling apparatus comprising a stretch of track used bypass'en er trains'havin relative-l short maxi- 23 v D mum brakingdistances and byfr'eight trains having relatively long maximum braking distance, and lRQtLDS operating under dangerous traffic conditions to give a restrict e indication on an approaching train at one place a given distance in therear ofthe dan er aoint orat another alace a reater distance in the rear of the danger point according as thetrain is of" V V the passenger 'or the 1 freight class.

Railway trafiic controlling apparatus comprising 'astretch oftrack divided into sections and used by passenger trains hav ing relatively short maximum braking distance a'nid by freight trains having relatively long maximum. operating w 7 C' a restrictive indication on an approaching train at a less-or: a greater distance in the braking distance, and means hen asectm'n'is occupied to give rear of the occupied section" according as the train is class.

5. Railway trailic controlling apparatus comprising a stretch of track used by trains of two classes having diiferent maximum braking distances, means operating under dangerous traliic conditions to give a restrictive indication on an approaching train at least at the greater of said distances in the rear of the danger point, trackway apparatus eli'ective when actuated to prevent said restrictive indication until the train reaches a point at least at the lesser of said distances in the rear of the danger point, and means carried by trains having the lesser maxi mum braking distance for causing actuation of: said trackway apparatus.

(3. Railway traffic controlling apparatus comprising a stretch of track used by trains of two classes having different maximum braking distances, means operating under dangerous traffic conditions to givea restrictive indication on an approaching train at least atthe greater of said distances in the rear of the danger point, trackway apparatus effective when actuated to prevent said of the passenger or the freight restrictive indication until the train reaches a point at least at the lesser of said distances in the rear of the danger point, a transformer located in the trackway for controlling said apparatus and having a large gap in its magnetic circuit, and a magnetic member carried by each train having the lesser maximum braking distance for reducing the ap in the magnetic circuit of said transormer.

7. Railway t-raffic controlling apparatus comprising a stretch of track used by trains of two classes having different maximum braking distances, means operating under dangerous trailic conditions to give a. restrictive indication on an approaching train at least at the greater of said distances in the rear of the danger point, a relay located in the trackway and effective when energized to prevent said restrictive indication until the train reaches a point at least at the lesser of said distances inthe rear of the danger point, and means located partly in the trackway and partly on trains having the lesser braking distance for energizing said relay.

8. Railway trafiic controlling apparatus comprising a stretch of track used by trains of two classes having difi'erent maximum braking distances, means operating under dangerous trafiic conditions to give a restrictive indication on an ap 'iroaching train at least at the greater of said distances in the rear of the danger point, a relay located in the traclnvay and effective when energized to prevent said restrictive indication until the train reaches a point at least at the lesser of said distances in the rear of the danger point, a transformer located in the trackway and having a large air gap in its distances, means for supplying said magnetic circuit, meansfor supplying the primary of said tl'tll'lSfOllTlOl with alternating current, means for su 'iplying said relay with alternating current from the secondary of said transformer, and a magnetic member carried by each train having the lesser braking distance for reducing the air gap in the magnetic circuit of said transformer.

9. Railway trafiic controlling apparatus comprising trackway means normally operating to give a restrictive indication on a train when the train reaches a given location in the rear of a danger point, andv apparatus located partly in the trackn'ay and partly on a train for atlecting said means to prevent said restrictive indication until the train reaches a location closer to the danger point. i

it). In combination, a section of railway track supplied with. alternating track cin cnit current and with alternating loop current, and apparatus located partly in the trackway at the entrance to said section and partly on a train for reversing the instantaneous relative currents. I

11. In combination, a

polarity of one of said section of railway track supplied with alternating track cir cuit current and with alternating loop current, a relay for causing one of said currents to beef one instantaneous relative polarity or the other according as said relay is energized or dc-energized, and apparatus located partly in the trackway and partly on a train for energizing said relay as the train enters said section.

12. Railway trailic controlling apparatus comprising a stretch of traclcdivided .into sections and used by trains of two different classes having different maximum braking section with alternating train governing current, and apparatus located partly in the trackway and partly on each train of: one class but not of the other for reversing the in tantaneous relatii 'e polarity of said current.

13. In combination, a section of railivay track supplied with alternating track circuit current, means for supplying said section with alternating loop current of one. instantaneous polarity with respect to said track circuit current, and apparatus located partly in the trackway and partly on a train for reversing the relative instantaneous polarity of saidloop current as the train enters said section.

14. In combination a stretch of railway traclrdivided into sections, a transformer for each section having a large gap in its mag netic circuit, means controlled by tratlic conditions in advance of each section for supplying alternating current to the primary of the associated section, a relay for each section supplied with current from the secondary oi the associated transformer, a magnetic me1nber carried by a train for reducing the gap in the magnetic circuit of each said transformer, and traffic governing means controlled by said relays.

15. In combination, a stretch of railway track divided into sections, a transformer for each section having a large'gap in its magnetic circuit, means controlled by traiiic conditions in advance of each section for supplying alternating current to the primary of the associated section, a relay for each section, a pick-up circuit for each relay supplied with current from the secondary of the associated transformer, a holding circuit for each relay controlled by traiiic conditions in the associated section and by traffic conditions in advance of the'associated section, a magnetic member carried by a trainvfor reducing the gap in the magnetic circuit of each said transformer, and traflic governing means controlled by said relays.

16. In combination, a stretch of railway track used by trains of two classes having different maximum bra-king distances, a gauntlet track having two pairs of rails for trains of said two classes respectively, a switch for diverting trains from said stretch to one pair of rails or the other of said gauntlet, means normally operating to give a restrictive indication on a train at a given location in said stretch when the train approaches said gauntlet under unsafe traflic conditions, apparatus located partly in the trackway and partly on trains having the lesser maximum braking distance for affecting said means to delay said restrictive indication until the train reaches a second location closer to the gauntlet, and means associated with said switchfor preventing said apparatus from functioning when the switch is set for the passage of trains having the greater maximum braking distance.

In testimony whereof I aifiX my signature.

HOWARD A. THOMPSON. 

